I have a crack on an inside corner of an outside wall (a gap really) that I need to repair. Some PO had filled the crack with caulk. I have chipped out all of the hard brittle caulk which has left me with a crack of about 3/8" wide. Its gets to about 1"' inch wide in a couple spots where the plaster had crumbled. The crack is about 1" deep when I insert a screwdriver and runs the entire 11' height of the wall.
Of note: When removing the wallpaper, I found evidence of minor surface mold which indicates to me that cold air is coming in through the crack causing condensation in the area.
How should I repair it? Simply putting up mesh tape with a couple layer of joint compound seems inadequate to me. Couple of ideas I had for filling the crack were: joint compound, caulk, or expanding foam
(click to enlarge)